Semiconductor devices for networks and digital home appliances are required to achieve higher performance and higher functionality, as well as lower power consumption. This leads to miniaturization of circuit patterns, and in response to the progress of such miniaturization, pattern collapse of the circuit patterns becomes a problem. In production of semiconductor devices, cleaning steps are performed many times in order to remove particles and metallic impurities. As a result, the cleaning steps occupy about 30 to 40 percent of the whole process of producing semiconductors. If the aspect ratio of a pattern becomes high as a result of the miniaturization of semiconductor devices, the pattern is collapsed when the air-liquid interface passes through the pattern after cleaning or rinsing in such cleaning steps. This phenomenon is the pattern collapse. In order to prevent occurrence of the pattern collapse, the patterning design needs to be changed. Further, the pattern collapse may cause a reduction in the yield in production. Thus, methods for preventing the pattern collapse in cleaning steps have been desired.
One known effective method of preventing the pattern collapse is formation of a water-repellent protective film on the pattern surface. This water-repellent protective film needs to be formed without drying the pattern surface. Thus, the water-repellent protective film is formed from a water-repellent protective film forming chemical liquid that can impart the water repellency to the pattern surface.
For example, Patent Literature 1 discloses a cleaning technique in which the surface of a wafer having a pattern of recessed and projected portions formed from a silicon-containing film is modified by oxidation, for example, and then a water-repellent protective film is formed on the surface using a water-soluble surfactant or a silane-coupling agent, so that the pattern collapse is prevented.
Patent Literature 2 discloses a cleaning technique in which a water-repellent protective film is formed using a chemical liquid containing any of alkyl amines and alkyl isocyanates on the surface of a wafer having a pattern of recessed and projected portions formed on the surface thereof from a metallic element, so that the pattern collapse is prevented.
Patent Literature 3 discloses a cleaning technique in which a water-repellent protective film is formed using a chemical liquid containing an alkyl phosphonate on the surface of a wafer having a pattern of recessed and projected portions formed on the surface thereof from a metallic element, so that the pattern collapse is prevented.